With the popularity of mobile communication equipment, the demand for an improved mobile base station design that is compatible with various communication protocols, economization of base station constructing resources, small size and easily concealed, etc. To occupy a larger part of the base station, the antenna must have a smaller design and be compatible with various communication frequency bands, as well as to realize the polarization isolation of transmitting and receiving signals on the same antenna, etc.
To achieve the above purpose, the base station design requires a certain working bandwidth, a wider wave beam, a better front-to-rear ratio, ±45° dual-polarization, and a cross-polarization inhibitor. Meanwhile, in order to reduce the interference between signal transmission and reception, a high enough isolation degree is required between the two cross-polarization ports of the antenna. In the prior art, two cross-positioned dipoles are usually adopted in the design of the base station antenna because the dipole antenna has an omnidirectional diagram and wider bandwidth. However, the dipole antenna can only work properly in a quarter-wavelength distance from the metal reflector, limiting the working bandwidth. Designing a smaller antenna is difficult in this arrangement. Additionally, the traditional design of the base station antenna adopts a patch antenna. Compared with the dipole antenna, the patch antenna is a low-profile antenna, which can satisfy the requirement of a small-sized system. To improve the isolation degree of a dual-polarized feeding port, the patch antenna adopts balanced-feed way, which requires a complicated design of broadband 180° phase shifter in the feeding network, increasing the difficulty and cost. In conclusion, the shortcomings of traditional base station antennas create urgent problems that need to be solved for those skilled in this field.